1. Field of the Invention
The present invention relates to a method and an apparatus for clamping a rectangular parallelepipedic work.
2. Description of the Related Art
A conventional method for machining a rectangular parallelepipedic (or cuboidal) work is illustrated in FIG. 7.
Shown in FIG. 7 is a cuboidal work M which has the upper surface S1, the lower surface S2, the left side S3, the rear surface S4, the right side S5, and the front surface S6.
In the first step of machining, the work M is attached to the table of a machining equipment (not shown), with its lower surface S2 facing downward, and then fixed to the table by clamping on its left side S3 and its right side S5.
The upper surface S1 undergoes milling by a vertical milling machine or a vertical machining center (not shown) so that the reference plane is formed.
The work M is reversed, with the upper surface S1 as the reference plane facing downward, and the upper surface S1 is fixed to the table, with both the left side S3 and the right side S5 clamped. The lower surface S2 undergoes milling.
The upper surface S1 is attached to the table of a horizontal milling machine or a horizontal machining center (not shown), and the left side S3 undergoes milling.
The work M is turned 90° and the right side S5 undergoes milling, with the left side S3 serving as the reference plane.
The work M is turned 90°, and both the rear surface S4 and the front surface S6 undergo milling in the same way as mentioned above. In this way milling on the six surfaces is completed.
The present applicant has proposed a machine tool capable of performing the above-mentioned machining. See Japanese Patent Laid-open No. 8-155768.
As mentioned above, the conventional method of machining a cuboidal work requires that the operator attaches and detaches the work each time one surface is machined.
The conventional method that requires the operator to attach and detach the work each time one surface is machined needs much labor and long time and is liable to variation in machining accuracy.